Friday & Saturday, April 27 & 28:  Big Island Chocolate Festival.  The chocolate extravaganza includes a cacao plantation tour at Original Hawaiian Chocolate Factory, a college culinary competition and several public foodie and agriculture-themed seminars. Activities culminate 5 to 9 p.m. Saturday, with the indoor-outdoor festival gala.  Enjoy a host of sweet and savory culinary stations presented by top isle chefs, chocolatiers and confectioners. Fun chocolate activities include chocolate body painting. There will be food booths, unlimited wine and beer…